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Fatigue assessment of laser welded overlap joints with local approaches
The fatigue strength of laser beam welded thin sheet specimens made of steel was examined in a project several years ago. The focus of the present numerical investigation are the overlap welded joints with a sharp slot weld of various thickness, which were tested subjected to different modes of loading. The results are reconsidered using different local approaches. A structural stress concept, based on section forces, yields acceptable results, but it shows an influence of the sheet thickness. LEFM properly accounts for sheet thickness, but the different loading directions cannot be sufficiently correlated. A notch stress approach with a small dimension notch radius of r = 0.05 mm overcomes these deficits. It allows the description of the fatigue properties of all specimens with a single master curve and good accuracy. It is suitable to transfer experimental data to a real complex structure.